This are actually due for release on the 18th, as I understand it. Intel is 'fudging the facts' a little there, and has moved the release date forward in any case in a vain attempt to upstage AMD, which is due to release dual-core Opterons on 21st April.

The 840 dual-core processors will primarily be a lower-end workstation processor. For gaming, on the other hand, a single core P4 3.8GHz kicks butt on them as I understand it. And an AMD64 3800+ kicks butt on that!